Thread: Vertical Farms
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Old Posted May 3, 2010, 9:57 PM
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Why Planting Farms in Skyscrapers Won't Solve Our Food Problems


May 3, 2010

By Stan Cox

Read More: http://www.alternet.org/food/146686/..._food_problems

Quote:
- After doing a very good job of describing the terrible toll that agriculture takes on soil, water, and biodiversity across the globe, Despommier's article lays out a proposal to replace soil-based farming with a system of producing food crops in tall urban buildings-to, he writes, "grow crops indoors, under rigorously controlled conditions, in vertical farms. Plants grown in high-rise buildings erected on now vacant city lots and in large, multistory rooftop greenhouses could produce food year-round using significantly less water, producing little waste, with less risk of infectious diseases, and no need for fossil-fueled machinery or transĀ¬port from distant rural farms."

- Despommier describes how one of his scenarios-which are based on the use of hydroponic or "aeroponic" methods of growing plants without soil-might work: "Let us say that each floor of a vertical farm offers four growing seasons, double the plant density, and two layers per floor-a multiplying factor of 16 (4 _ 2 _ 2). A 30-story building covering one city block could therefore produce 2,400 acres of food (30 stories _ 5 acres _ 16) a year." By extrapolating numbers like those and assuming extraordinary leaps in technology, as well as the repeal of Murphy's Law, he has made such a convincing case for vertical farms that, he claims, "many developers, investors, mayors and city planners have become advocates." Time magazine has run a generally positive story on the concept. And an Australian architect is currently planning to build the first full-scale vertical farm, in China.

- Even if vertical farming were feasible on a large scale, it would not solve the most pressing agricultural problems; rather, it would push the dependence of food production on industrial inputs to even greater heights. It would ensure that dependence by depriving crops not only of soil but also of the most plentiful and ecologically benign energy source of all: sunlight.

- Agriculture as it has always been practiced-call it "horizontal farming"-casts an extremely broad, green "net" across the landscape to capture solar energy, which plants use in producing food. Photosynthesis converts a small percentage of the solar energy that falls on a leaf into the chemical energy in food. But that small percentage is enough; sunlight is plentiful, and left to themselves, plants do not have to rely on any other sources of energy to grow and produce.
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